Fixed by-pass condenser



Sept- 2, 1930. R. G. EVANS 1,774,875

FIXED BY-PAS S CONDENS ER Filed May l1., 1928 current will iicvv througl irateuied JL lCE GEO. EVANS, QF IJETROIT,

FIXED'BY-PASS CONDENSER Application led May 11,

This invention relates to radio frequency A tying circuits, and-the principal objec Jhereof is to provide a simple, novel, and eiiicient fixed lay-pass condenser particularly adapted for use in tuned radio frequency cir cuit" which. condenser will be inexpensive to manufacture and highly eiiicient in operationg also to provide a novel hook-up for such circuits utilizing my fixed 1ny-pass condensers in such a Way as to edect an electrostatic balance across the filaments of the radio tubes. eachv fixed condenser having at the center of this electrostatic balance a conductor having its own dielectric, and each condenser being connected in such a. that the A power Vthe condenseruntil said electrostatic balance is reached.

Another object of the invention is to obviate some Weil known defects in connection with. such radio tubes and their circuits, since no tuned radio frequency ampliiier Will be eflicient unlessit can be balanced against' oscillations and its regeneration controlledz My novel lixed condensers forni a means for balancing such circuits or systems; or for neutralizing same; and when use.. R. F. amplier circuit a ba vice, and also allows a certain ai generation to talre place but cor variable resistor in the positive plate lead. A. small anioiuit oli is very desirable in an 1 l?. amc i but not desirable in an a io sy in; and my condensers 'can be used to stop this regenera tion in an audio systema Other minor objects the invention will be hereinafterset forth.

I Will explain the invention with reierence to the accompanying dra rings which illus trate one practical embodiment thereof to enable others familiar with tlieart to adopt and use the saine, and I will summarise in the claims the novel features of construction and n n Luc Lio novel combination of parte for 'which pro frequency amplifying circuit, also showing therein the hook-up for eight fixed by-pass 1928. Serial No. eugene.

condensers orobtaining most edicient results.

Fig. 9, shows the same circuit as in Fig. 1 but equipped With` iour of my novel by-pass condensers to accomplish the saine results.

Fig. 3 shows diagrammatic lly the hookup for one of my condenser-s h res vect to a tube socket, R, F.. coil., A and Bl batteries. i

Fig. lis a perspective vieiv of my novel r'lxed bypass condenser, detached.

Fig. 5 is au enlarged trarfveme section through the condenser shown in Fig. il.

In 1 the lioolr upior live-tube tuned radio frequency amplifying circuit is shown, said circuit employing two stages of radio frequency amplifie on and "he detector circuit, s of audio irequency anipliiicatiou and an oi out tr. isformer. 'Ihe antenna l is commel to mound 2 through primary coil 3 oi the tun transformer el. t' condary Winding i is tuned by a variable condenser i to the i? The stage o .dio lrequency ampli- 'L/ having iilament elcc 4 89 f id electrode Si and plate elect-rode l p ut circuit ci tube 7 across the grid nt 8 connected. circuit t and ti. The output circuit of tube Winding 11 of the radio cuplii ins). "ner .12 one end connected to ,a source y l 3f; tial (about 70 volts). jai? v udine; ci transformer by variable condenser 14, and the input circuit of electron tube 15 ormii f the i of Vrudio freo uency ami: liiication. The r Itput circuit of "ube l5 includes primary Winding.' 16, of coupling trarsiforiner 1T and a source of B battery potential (about Y() volts). The second- 18 tuned by variable condenser 19 and iication includes trede 'equency of the signals.

with the tuned...

connects through grid leal; and grid con- A cluding the primary coil 26 of audio transformer 27'and a` source of B battery potential (about 90 volts).

The secondary 28 of audio transformer 27 is connected in the input circuit of the last tube 29 which input circuit also includes a C batte-ry 80. `The output circuit of tube 29includes the primary coil 31 of an output transformer 32 and a source of B battery potential (about 180 volts). The secondary 33 of output transformer 32 is connected across the responsive device 34 which may be a. loud speaker.

r1`he filaments of all the tubes 7, 15, 21, 25 and 29 are heated in the usual manner from an A battery.

I have found that unusual good results in radio reception are obtained by hooking in eight fixed by-pass condensers 40 in the above circuit, one such condenser being shunted across the filament of each of the tubes 7, 15, 25 and 29.1espectively, said condensers 40 each being of small capacity usually 1.0 mfd., and producing an electrostatic balance across the filaments of their respective tubes.

One of the remaining four fixed by-pass condensers 40 in Fig. 1, is shunted across the negative A battery wire leading from the negative filament 8 of the tube 7 and the positive B battery connection of primary coil 11. Another condenser 40 is similarly shunted'across the negative A battery wire leading from the filament of tube 15 and the positive B battery connection of primary coil 16. Another fixed by-pass-condenser 40 is shunte'd across the negative A battery wire leading from the filament of tube 25 and the B battery connection of primary coil 22; and the last fixed by-pass condenser 40 is similarly shunted across the negative A battery wire leading from the filament of'tube 29 and the positive B battery connection of primary coil 26.

In Fig. 2, the same tuned radio frequency circuit is shown as in Fig. 1, but the' eight fixed by-pass condensers have been replaced by four of my novel three-electrode condens.

ers 41 for accomplishing the same result. @ne condenser 41 has its two outer plates shunted across the filament 8 of tube 7 the central fl'xed plate of condenser 41 being connected with the B battery wireleading to primary coil 11, said condensers 41 producing the same results as the two condensers 40 for tube 7 in Fig. 1. A second condenser 41 is similarly connected in the circuit of tube 15. A third condenser 41 has its two outer plates shunted across the filament of tube 25 and its central plate connected to the B battery wire leading to primary coil 22; and the fourth condenser 41 is similarly-connected in the circuit of tube 29. My four condensers 41 therefore in Fig. 2, replace the eight condensers 40 in Fig. 1.

In the arrangement shown in Fig. 2, in-

stead of by-passine the. high frequency currents of the plate circuit backto its own tube in Figs. 2 and 3, preferably comprises a casing 41n of rectangular shape, having one end open and the other closed, said casing 41 having offset feet 41b extending from the side in order that the casing which houses the condenser parts may be conveniently mounted above a panel board in such manner that there will be as little as possible condenser act-ion between the panel and condenser.

. Vithin the casing 411 is a copper plate 41C, having a projection 41d extending out of the open end of the casing; said plate being coated with a hard rubber dielectric composition 41e thoroughly insulating the copper plate 41, the same being capable of withstanding voltages up to about 300 volts.

Around the dielectric 41E within the casing are wrapped two super-imposed conductors 41t and 41g each comprising strips of tinfoil inserted between paper dielectric strips 41h, said conduct-ors 41t and 41g being superimposed and then together wrapped spirally around the plate 41c in order that the plate will be disposed centrally of the wrapped conductors. By the above construction the conductors 41f and 41g will be insulated from each other and from copper plate.

At the outer ends of each of the wrapped tin-foil conductors 41r and 41g are copper wires 41k and 41m which extend entirely through the casing from the open end, adj acent the portion 41d, through spaced perforations in the closed end of casing 41` said wires 41k and 41m being suitably insulated from the casing, by means of sealing wax o1' the like.

Between the wrapped conductors 41" and 41g and the casing 41a is an insulating sheet` 4lp preferably wrapped round the wound condensers to retain the saine in fixed position. The open end of the casing 41a is preferably closed, after assembly of the condenser, with sealing wax or the like, the members 41, 41k and 41In projecting therethrough.

In use, my condensers are connected in the circuit as shown in Fig. 3, with the conductors 41r and 41g respectively shunted across the filament of the radio tube, and the copperplate 41 connected to the positive wire leading from the B 'battery to the primary Ian Winding of the related transformer, thereby establishing an electrostatic balance across the filament of the tube, and the current from the A battery in Fig. 3 passing through the condenser.

I do not limit my invention to the exact form shown in the drawing for obviously changes may be made therein within the scope of the claims.

I claim 1. A- fixed by-pass condenser comprising a. plate ol conducting material; a dielectric around saidgplate; a pair of superimposed conductors each interposed between dielectric strips and Wrapped spirally around the copper plate;v and electric leads for the Spirally wrapped conductors and the plates.

2. A fixed by-pass condenser comprising a casing; a. plate of conducting material in said casing having one end projecting therefrom; a dielectric around said plate; a pair of superimposed conduct-ors each interposed between dielectric strips and Wrapped spirally( around the copper plate within the casing; and lead wires for the spirally Wrapped conductors insulated from the casing, the plate, and from eachother.

3. In a condenser as set forth in claim 2.

perforated feet offset from one side of the casin for attachiner same s aced from a su g e P v port.

4. A fixed by-pass condenser comprising a casing; a copper plate in said casing having one end projecting therefrom; a dielectric around said plate; a pair of superimposed tin-foil conductors each interposed between paper dielectric strips and Wrapped spirally around the copper plate within the casing;

and lead wires for the tin-foil conductors extending through the casing and insulated from the casing and from the copper 4plate and from each other.

5. In a condenser as set forth in claim 4,

perforated feet offset from one side of the easing for attaching same to and above a support.

6. A double voltage by-pass condenser l comprising insulated and superimposed spirally-Wrapped condenser conductors adapted to receive an .impressed voltage; and an insulated condenser plate at the center ofthe spirally wrapped conductors adapted tov receive a second impressed voltage.

RUSSELL GEO. EVANS. 

